Process and apparatus for testing wattmeters.



- E. M. WILKINS. um mmnuus ran warme w.m1m'mzs. I Y D AUG.

905,966. l APPLEKOA'I. 01 ILE 12 1907 Patent! Dm. 8

of which the followin is a specification.

- UNITED FSTATES- OFFICE EDGAR M. WILKINS, omfib1ixco, MEXICQ.

' rnocnss ARD nrmnws'ron. nsrnw'd wnrnmnms.

m..oo5oee.

kppllcation 111011 Aug-t 12 T0 all'whom it may concern:

Be it known that I EDGAR-M. W1LKINS, of Mexico city, Mexico, l1 eveinvented a 'P10C- ess und Apparatus for Testi1ig WattmeterS,

The invention r e ates to an improved ine thod for calibrating orstandardizing service n1eters such as' are usegl on eleetric oireuits,although it is poss ible that the inb bvention herein disolosed may alsobe found applicable to the Calibration or standa,rdiza t1on of othermeters.- The type of meter here more particularly had in mind, hdwever,und with relation to which the present in- 15 vention is described, isthat known es the integrating wattmeteff the induction type (being inreality a watt-hour meter), which type oonsists, es is well underStoo'd,of a motor whose roter oonsists of' an a'luminum .20 disk mouri6d torotate on a spindle und actuated by; the combined a2otion of thepotential and oungarlt flux of the statoxg, and retarded by the finx ofa permanent magnet. 'My invent in may also 'be applied, however,

5 130 the oommutating type of meter used on direct current circnits.

' The object of my present invention is 130 provide a method both moreaccxirate and also very much 1n'ore rapidthan in eommon use forstandardizing mete1s and adjusting them to accuraoy.

lt is well known that' meters of diflerent types, diflerent mamifactureo1 different capacity have correspondingly difierent charaeteristics,and heno e give diflerent rogistxatin for the Same. load 01 forvariations. fronr the normal of the voltage, fre 1uency o1 temperature.-This has holen fully explained, f0r example, in a paper'by "illia1nBxadshaW on 40 Tho Maintenimce and Calibration ofServioe Meters,publishecl in the roceedings of the National Electric Light ssociationfor 1906. Beo1use 0f the fact that the rate of regist-mt-ion 0f a mctoris not strictly proport-ional to the'l'omd upon it for all loads,but ingc'neral only for two loacls for a given setting,

'it is desiruble, not mcrely to set a met'er to register correctly onelo'acl, say full load, b ut also to tust 1ts reg1stratlon at one 01'more' 0tl1e1loads, in particularavery light l oud ab which the moter isliable to vnry more widely frmn the normal.

My method consistsbriefly in two steps, nau'nely, first, in calibratinga secondary standmd integrating meter, preferably of Speciflcafiion oiLettezi Patent. J

1 07. s5mu m. ass4u standardized, bjcomiiarison with dKelvin balance t'omealsure the-watts -end a time riod equal to the coirect Period ofrotation of the meter when loaded to the test load and secondly,00mparison of the said secondazry 'standard virhen thus calibrated withthe service meters by means of a s eeial method tobe hereinafterdeseribed. 0th steps 'mvolve as an essential element of the invenofinstsintaneous presenta tion to the eye,

es by an electrically operated photographic shuttt or' a revolvingmirrpr, Whi0h errangeme'nts Will behereinafter described in detail.

have' q, disk 01' cylinder on oh a Spot of pa'int 1s put for countingthe 1evolutions.

drawings, wherein gare 1 illustratesdiagrmmatioally the arrangement ofthe 'el emen s and eleclprical connetztions for standardif'ng arotatingmeter for alternatin currnt by m6ans of Shows diagmmmatically tharrangement of the arts und electr1cal lconneotions for stan ardizingsimultaneousl}* o1 successivelj a nutnber of' alternating cu;rrentserviee me tets by means'of a secondary standard or standardized rotatingmeter; and Eig. 3 %llustrat s an alternative method for perpl iedto direct current meters. In these drawin s every referencenumeralandletter re ers elways t0 the same part.

In Fi 1, as wel l as m the F1g. 2 the charact ers und B designate thebus-bars or the same type as the Service meters 190 b e fingers c" areinsulated from one another und.

Pa tented rm. s, 190a.

ti on the obser vafoion during rotation of a Spot or m'ark upon themeter disk by means Wh.ieh may be accc' mplished in various ways,

As noW manufctured all inteating meters -:The prinoi les of my inventionare well and clearly i ust rated 1n the accompanying the penduhim and(elvinlibalance; Fig. 2.

orming this calibration or standardizat1on, thi's diagmm showing alsothe method as ap- A meas'urer such als sijpendulum having apeconoctedi-espectively with terminals d manner is.provided with aplurality of equi fingers d. spaced so as simultaneously to bars B- B.Ordinarily, howevet; it Would Ing-mter G so that' it may'be t'ested atfull the high-tension primary f? of a gransformer cirouit, --a's shown.

-combmat1on of autotrgnsforfl1ers 1n cascade 'into a, greater number ofst'eps so a s to obtain .a sufi imently close regula'tion.

tion. The loW-tension secondaryf=of sa1d of only a few vo of a secondautotransformer D which in like distant taps d brought down toc0ntaotbosses d disposed circularly about ehe pivot (Z of a oontaot-leVer d, Which like the levor c is provided with twoinsulatedcontactcontact with two adjaoent bosse s d. The fingers d am in turnconnected with the terminals e, e of a third aut0transformer E, which isalso provided with' a plurality' of equidistant taps e in like -mannerconnected to the respeotive contact-bosses e which are disposedoircularly about-the pivot e ofa contact-leve'r e, which latter carriesa pair of contact-fingers e" so disp osed as to contact simultaneouslywith two adjaoent bosses e" aS shown and so that in slidingalong tl1ebosses e oneofthefii1gets is always inoontaub with one of said bosses.The fii1gers e are connected to the ends of an induct1ve re-' sistanceo1 choke-coil a, the center of which is connect e'd by a lead e? to th epivot e. The choke-c oil e prevents the segment beoween the tapse"covered by the fingers e from being short-oirouited, -while at thesame time not interfering with the flow of current in the leacl e".- lf,instead of this arrangement, a single oontact-finger on the leVer e wereemployed, the shifting of the lever would necessitate eitherbreakm'g theCircuit between bosses o1 short-circiting the segments of thetransformer E, botli of which arevery objectionablejbut with thi'sarrangement both these contingencies are pre vented.

The pivot e' of the lev r e 'is eleotrically coni1ecte by a conductor fto one pole of F, the pole f of said rimary bii1g 0011316611,- eddireotlyto the po e 01' bus-bar B of the lt will be seen tha t thisforms a meazns-of adjusting very clos ely the total electromotive forceappliod to the terminals of the"priniary'f. 1*or exzimple, if, as, shownin die draw1ng, the 'aut0transformers C, D, and E are euch divided intoten equal steps or segments, an adjustment of voltage appli ed to can Hemade t odnethousandth part of that between the bus-==g riot benecessar'y to use mor'ethan two autotransformersin casoade, i phesebeing divided The -purpose of the transformef F is '00 provide a;full-load ci1cuit fpr thest anda;rdizload witho1it 'unnecesisaxypbwer-o0nsumptransfimex Will therefore, give a Potential lts Thecurnent-circuit or load-cirduit for testing iri'cludes, beside thesecondar'yf of the transform'er F, a continu ously variable rheostat H;the current coils j of tl1e Kelvin balance J und the ourrent-coil g ofthe meter G; all of whioh a re connected im series as shown; but betweenthe metev-coil g and the othe1 elements of the circuit is inserted adouble-throw o1 ohange-over switch K. 'lho terminals k, k, of the switohK am oonneoted to the respeotive poles of oho coil g, and areobnneotible v eilternatively to the terminals k und k, and k aocordingas tl1e blades k of t he switoh am thrown to the left or 130 tl1e right.Wl1en thrown to the left the transformer F, Theostat H, balance ooils j,and meter ooil g aro all conneoted together i n series by t he switoh K,as shown. A so small secor'xdary transformer L wvith a trans- -formationratio of ten to one hats its low-tensionprimary l connected by leadsP,l, to the terminals k and k respeotively of the switch K; While theterminals of the hightension Secondary l* of said transformer areconnected by leads Z and l with the terminals k und" k of the switoh K.It will be seen that the transformer-L is 01 1t of 'action in Ruheleft-hand position of oho sWitch K, its

[ primary then being short-oiruitedand i ts secondary open-oirouited;l)ut on throwing the switch to 1ahe right, direct connection between themeter-oo1l andthe primary-cir ouit is cut ofi,- this c1rcuit being thencompleted through the primary ot 'the t'ransformer L, while ehemeter-circuit is complete l from the secondary l of the transformer L,throu h the .leads Z and l",the terminals k and f, sWitch-blades k, tl1e terminals 7c and k, and thence through the 'meter-coil g. The effeotof this fs 130 give 0 cufrent or load u 011 the me'ter in theright: bandosition of t e switoh K on1y one-tenth of tht whi oh ithas in theleft-harid position, while the adjustment of the balance J is undisturbed. 'lhe Potential-coils i of the Kelvin balance are of corse,connected (chrou h the usual resistance, across the-poles of o ecircuit, through'thesecondary 'leads b and 11 to therespectivogonductors B and=Bfl and th'e potential ooil gof the meter Gare in like manner oonneot'eel acrossthe poles of theoircuit as shown.

The saf)ls g? of tld1e mei1er bears the usual c eris g, a n on t 1e erihe of this 'd?s l?is laced a spot or marfi g zthi s mork is genera ypuhon by the manufacturers) which ;1s Obserined a1;intervalsT-corresponding 120 one 'complet rotatipn, through .a" phocoraphic shut1zer M, which is set to' what is oal ed the ii.1 s'tantaneousexposur%he length of whi0h' is so shortv as to show the rotating-spot gsubsla'fitially only in one position. For' comparis'ons sake afi3cedspot or marlt g is placed adjac entto the periphery of th e disk g,and.may or may not be accompariied by a graduated am g". Th6 adtialz1onsohthe arc g when used,"Shoul%spresent 3.6de- \grees auch, 01 in otherwords a hundredth .of 130 a revolut1on. The sluitter M 1s operated:bymeans of a time-measuring devic6 such as a .pendulum N, whoseperiod ofcomplete 01' d0uble-vi'biation' is'set to be eXa'ctly equul to the propdr tix n0 fo1 a-compl9ter9volution of the d1sk g Witl1 the givenlohd. 'I.herstemn .of the pendulum may be graduated,is at n* to.difiercnt settings of the bob n col'responding with diflerentmeter-oonstants. 'The;

pendulm N acts through a contactp0int n carried therbby und dipying intothe merc'ury cup O at the *end 01 nach swing to the left ai1d therebyclosing n circuit n across the leads b, b; which circuit includes a nelectromagnet P, Whose armuture p is mounted on tl1e actuating arm m ofthc shutter M. The -efl'ect of this arrangement obviousl is that-at eachswing to theleft 0f" Tho balance J is first mljusted to4ahe loacl forwhich the meter G is 130 be calibrated, say

thefull load of sai l 1neter, and ehe pendul-um N is also adjusted to aperiod equal to the correct period 0f 1rotation of. the meter under suchload,v as 'above described.

The current 0f alle secondary circui't is then adjuted till the beam 0[the balanceJ is exacitly balanced, thi s being; done by aprofieradjustment of the contact-lev@rs c, d, and e, and

' ofthe rheostat H the switch K being thrown to the leit as shown .infull lines in the Umw- At the beginnin of the observations,

. the disk g is checked y the finger until the spot approximatelyregisters with the spo t g at the 0 ening ofthe shutte'r.- Su pbsmg n owthat t 1e meter i s cine per'cent. s ow the disk g 'Will, in the p1opelrtime fo'r one revolution, complete only ninetymine one-hundreths of onerevomtion, und the spot g will eonsequc'ently at each openin of theshutter M occupy a position one-huncfredth 0f a; revo- .lution (that is;one division of the scale g) to thei'ight of'that which iflocacpied attl1 preced ing opening of the shutter; So ahnt; wi th therepeatedopenihg o f the shutter M, tghe sp0t Will appear to lie moving slowlyin.a

- direct1oi 1 Contrary to that 0 f rotatpion of th6 disk. O n the qtherhand, if the mete1-be fast, the spot 9 wil a paar to move off in fihesame' direction as t1e disk on successive o p6nings of the shutten and-theapparent movemerit Wil. be the exce'ss spe ed of the eratioIi orretardation of the nieter can be measu red at' this point, and theaccuracy-of megsrement will be inoreasgd ix'i prop0rtion cent. for oneresvol'ution, und within one-tenth If desirable the percen'tage ofaccelof one per cefitffor fien 1evolutions. T0 set then adjusted tillthe spot g" appegrs 190 stand comple tely still, that 1s, app'ex zrs atexactl'y jche same point on euch success1ve 0 ening of the m'eter.correctflythe co ntrol magnets are.

the shutter, thus indicating that t e period of revolution is correct.lt is to be observed that, in this operation, both hands of theopera.tor are free po adjust the drag-magnets or meter-coils. Aftertestin'g -and settmg the 'the switzch K is thrown to the right, theautotransformex andtheostat handles again aLdgustedlif n(ace'ssary)until the beam of the ba ance J is level, and the accumcy of the meterfor fu-ll loixd (er any uther des ired load) rheter G may be tested forone-tenth of the former load, with thga sarrie 'reading on the balanceJas before, it belgg understood that 'the spot g is t0 be obser edouble-vibration of the pendulum N to indicate a, single revolution ofthe mete 'r' disk.

tion to be tested to one-tent of one per cent. of the ori inal or fullload, -that is, to' one per cent. f t e actual load.

It may be observed tht the rheosta.t H should be one without steps assh0wn, o;nd permit ting continuous vm-iatiou of the 16- d at every tenthI T bis will enable'the accuracy. of the registrasistance in circuit, sothat the exa ct current necessa. ry tobring the beam -t0 a. balance maybe pass ed throu'gh the coils j, when the balancepea is 'properly set.The rheostat also perrorms the function of raising the power-factor ofthecirouit, that is, of bring- 1ng the current in the secondam circuitmo1e 'closely into phase with that 0 the primary,

thus counteracting the dephasing tendency of the a.utotransfornier. '1hependulum N is here Shovvn for simplicityS sak6 without any drivingmechanism, but it is t0 be umlerstoodthat said Pendulum would beordinarily driven by a c locktrain 01 in any othe1.manner common to thependulums of cl0cks 'lhe second step of my procqss isthat ofi se0ondarystandard, a s is illustrated in Fig. 2. In this Part of the PTOCGSS Imake use of a transformer Q hav1ng a high-tens'ion prima.ry g, connectedbyleads g, g 30 the respectivemains B, 'B, and ibs s econdar y g, whichis of few turn s so as t0 ive a; large 0111"- rei1t ab loW'tensiog, isdivide by a plur9lit-y o'f taps' g int0 a) number of segmen-ts to whichcorrespond contact-bosses g" disposed in a circulafi manner aboutthe-p1vot' of the contact-lever g" whiph is so arrariged as -toconixe(stflny' 0 11e ofi,th e bosse s i 1 with one pc)lia of thecurrent-Circuit R he. lev er g may be constr'cted like thelever e ofF1g. 1,

a'.s mdica.ted in ;the drawing' with a. pair of' Eig. 1, a. SiniPljermeth '0d iS here ;l 1 own. The- 110 s'tandardizing the servic6-metersfrm -the 1 prima.ry g, of the transformer is ta. ped a.t one end by aplurality of ta.ps g w oh are brought down to contact-bosses q disposedfor. connection wi1zh a contact-lever 13 connected to the lea.d g*= Y Inthis way t e finer fadjustment f the current-cirquit is provided Thesecpndary standard G is shown as dispo sed centrally of a group 0fservice-meters A which a1e t0 betested or standardized.v

One of the terminals of the current-coil of each of the meters A may bepermanepty gonnected to one end of the se condary w1n mg of thetransformer Q by means of the cirv standard G, and the current-cils aofone of -or both', these being directed toward a small way from acentral zero-point as shown. a convenient distance from the standard G;

the selrvieemeters A. Bef0re making' the test, the potential coils a g?0f all the meters are preferably connected i1p with the line by ngeansof the leads b, b, so as to warm u the meters and have them in normalcon 1tion When the test is made. Each 'of the service meters A is roviddwith a spot 0r mark w upon the dis thereof, and a stationary scal'e aplaced-' adjacent theret0 as shown in th-e drawing, this scale beingpreferably graduated in hundredths of a circumferen ce eaih is placed atelescope U o1 a focusing lamp V,

mirror g placed 011 the shaft 0f the meter G; Both the telescope .U andthe lamp V are focused upon the scale a 0f any one of the service metersA, as 'm dicated by the ray-lines u, it being ux'1derstood, of c0urse,that a second mirror may be usedvyh6n necessary t0 throw the' light downin a Ve rtical dir6ction, as where jthe scale a 'is horizontal, b'eingnacessarily so representked in the diagriun: It is also desirable 130h&ve a cylindric al scren 01 diaphragm N inClosin'g the meine? G andhaving openings w and w there inin position to pegm1t the assage cfthe'light-rays bejzween the mirror g and the telescope U.l am V,- v andsdale-disks a 0f the meters A. All but one 0f these openings w m'ay, toavo'id COD- fu'sion, be 010sed by diaphragms 41P-Whil'e the metercorresponding to' the openi ng .Whichis left open 1s' being calibralted.

VVhere the telesco e and focusinglamp are used conjointly {eheightfrorg1 the latter will b'e thrown instantaneously upon the sCa)e"ofthe mete'r being tested When the mirior g?is directl in th e properangular position to reflect the light from the lam The light so flashedupon the scale Will disclose the momentary osition Cf the 'spot a on themeter-disk, which is obServed through the telescope U, und thereflection being momentaneous the spot Will appear to be standing stillat the given point 0n the scale. 011 the second revolution of the met6rG the same thing will take place, and

upon the meter 'scale.

if the meter under test 1s correct, the spot awill ap ear at the same-point as before, and

so 011 or successive revolutions, whereas, if fast or slow, it willappear to m ove slowly 01f to the right or left as observed through thatelescope. In this ease the rate of ac- .elertion or retardation may bemeasured,

if desired, 'and the meter set 1:0 the right speed by adjusting thecont'rol-magnets. As soon as one meter has been tested, the sW1tchlevers is shifted to start up the next meter which is tested in-turn, andthus a large numberof meters may be successivel tested rapidly, andwithout any change 0 adjustment of-the testing apparatus other thanabove indicated. 1 In general a meter can. be tested with suflicientaccuracy according; to this procepss by a ingle revo1ution of'th6shaftanother revolutiqnhavipg been first aliowed 'the meter to nse fromzero to normal velcity. Although. ;nore than one Spot might be u'sed onthemeter-disk for the pur ose of 'testing iriless than one revolution,do not deem this ad-visable; as the rate of rotation may be slightlydifferent from difierent arts .of

the revolution;making the first half, for example, ap ear longer orshorter than' the s6cond ha f. -Where the telescope U alone is us ed(without the fofzusing-lamp) the m(ater-scales will be crmtinuouslyillummated, and where the focusing-lamp V is used alone,

the osition of the spot a may be observed Y directly upon the scale,bein kept in sub- '-stantial darkness, exce t for t e momentaryillmination from the amp V. In Place of using thdtelesc0pe U the eye maybe plaized at thisj 0ii1t above 0'1 below the lamp and the mirror g ifslightly concaved Will present to th'e eye difected at the mirror amagnified .in'1age1of 'the scale of .shorter In the a b0ve 1hanner, themeter A may be adjusted to correct registration 'at any given load, andthe variatio1'1sfrom correconass -may then be tabulated by testing underany other load. EVen where the load-charac' teristics of theserv1'ce-meters are t1e same as. the standard by which they are tested(which will be the case if they a're of the same type and papa0ity), itisjgenerally advisable t0 'test them ab two loads, one heavy and oneliqht, as casual defects, such as undue frictiori o?bearingggear-trsiin, etc. cannot otherwise be detected.

' ice n1etercalibration, an

In Fig. 3 is shown a somevvhat difl'erent and simpler method of ca 'ngout the servfor the sake 01 ilhistrating tlxe' pssibilit-ies '0f mypmcess I have also shown it in this fi re es applied 130 direct-currentsystems. he direct-current standnrd meter is shown at G, and theservice-meter being teste(l at A. The potential coils (in 'thisv casethe armatures) 11, 12 0f both meters are Connected in paral lelby leads13, 14 t-o the main-conductors 15, 16 01': the power'circxiit while thecrrentcoilsl7, 18 are connected in seriesin a circ uit 19, which isenergized by any suitable W- potential source" 0f currei 1t, S11Cll as afeW storage cells 20 (or the eurreht may be derived 'by well-knownMethode from the powereircuit) and eontains a regulating device,illustratedas a the0stat 21. Inscead of tl1e light-relleet-ing apfaratus 0f Fig. 2 thereis provided a branchcirdit X counected across themains o1 otherwise electrically energized; this cireuit c0ntaining theelectromagnet Y wl1o se armature y' is secured tothe 0 erating-arm z ofa photographic sl1uttel E disposed in line with the -zero of lahe cale22 of the meter A, whereby the SPO1) 23 on the disk 24 thereof can -beobserved in its position relative 120 st'1ch scaleduring tl1e momentaryopenlng o'f the shutter. The Circuit X is normally open at a pair oft'erminals x, whieh may' be, if de- -s ired, in the form ofmercury.cups,- Wh-ich are electrically eonnected b T means of a pair ofradial arms 10 011 tl1e sha t 25 of the met er G, said ar1ns carryingbrushes x in position to contact with the terminals x.

- The terminals x should subtend an angle less than 180 degrees attheaxis 0f the nieter, Elaced at the same angle,

whereby1he brus es x simult aneouslyficontact only 0 nee in eahrevolution 'with the terminals m, theriaby closing the bianchcircuit X,and aCtuating t-he shutter Z. The p0sitiion 0f ehe. spot 237 0n themeter-disk is then observed at every opening of the shutter in the Samenianner es the spot g in Fig. 1, and the meter set accordingly; v

v In testing dirkect-current meters on light' loads it is desirable tocom} are with the standard meter ab full loagl Which aveids errors duetochange of loadeharactexistic 0f this typev and insures accurateresults.

duced 130 one .tenth that onthe mefer G. In this casle the Position ofthespoe23 is 0bser vedenly atevery tenth openingf bf the shutter. I

It is to-be' obse1vd that in all measure .sisting in setting ments on mysystem, t he operator has both hands free to adjust the metersimultaneously with obser'vation, which is one great advantage of themethod.

While some of th'e features herein dsCribed are limited to the use ofalternati curren't, it will be understoodthat in genera the system isapplicable t0 any kind 0f cur'- I rent, and. polyphase eonnectins, forexmn l)le can readily be devised by those skil ed in the ait. I d0 n0tconsider my invention limited in its form er scope of modificationotherwise than may be inferfed from the reasonable constructi on of myelaims.

Hawing thuS described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. The process 0f testing rotary registering meters having a spot 01mark upon a rotary element of the ri1eter, whioh consists in setfiingthe meter in rotation under any desired. load, momentarily di.sclosingto view the -angular position 0f seid spot at the expiration of fixedinte1vals of time, compar- .ing the amount of angularmovement therebyfound wit-h the proper a'ngulan movement for the given loa-d and time,and dedu-cin'g therefrom 'the faet of acceleration ojr retardation 0fgaid meter.

2. The process of testing rooaryregistering meters hav'1ng a spotor'mark upon a rotary art 0f t he meter, which' consists in 'setting themeter in rotation under any desired Joad'momentarily disclosi ng to viewthe angular osition 0f the spot 01' merk at the expiration of a knowninterval 0f time, and so adj usting seid meter that 'the amount ofaotual rota.tion so obs'erved shall be equal t0 the correct amonnt ofangular roftation for the given load and time.

3. .The proc ess 0f teSoing rotary registering meters-having a spot 0rmerk upon a. 10

tating Part of such a meter, and having a fixed spot or mark adjaci1t tothe path of seid Totalsing spot er mark, said procias's nensisting insettingsaid meter in rotation under any desired l0ad, mQasuring the loadux 1gler wh ich seid meter is 'pera4ting, monientarily disclosing t0view tlie Position of the rotatingspot or merk relt1ve tothe;=fixed spotr ma'rk at the end of intervals of tinhe eurreSp0nding t0the properperiod of rotatin of said rot'ating spot or ms.rk anddeduc' therefromthe aeceleration Orretardation% sa.id meter. 4. The process of te'stingrotary register- 'ing meters having a spo't 01 1nark u on a rotatingpart ef such anqeterand Es.

fixed spot er markadjacent to the p.ath 0 fv -Saidw'otating Spt 01'merk, seid proc'e9s 0011-- seid mtater in rotatienunder any desired loadu'nder whichmaid meter' is' operati1'xgymomentarily disclosing to vieWthe osition 0 fsaid rotating spot 01' mark relative to the or mark at 10fixed spot 01 msirk sdjsoent to the path of 3'5 marks ab intervalscorrespndiflg to the element for the giren load r some multiple6%shutter arranged in osition to 'observe the thecnd of intervals oftime corresponding to the proper period of rotation of said rotatingSpot or merk, and adjusting said me ter so as to make the rotating spotor mark appear oonstantly in the same.@osition relatixe -to said fixedspot or mark. 5. The process of testing rotary register- :ing metershav1'n a spot or merk upon a. ro-

' tating element 0 such meter, and haz1'ng a said rotating spot or markwhereby the angular position of the latter can be obse'rxed, seid process consisting in settingvsaid ineter in rotation under any giren load,measuring said load, arranging a photographlcshuttiar in Position forthe obseruation of said Spot or mark, actuating said shutter to open andclose instantane0us'ly at the expiration of inter=rals of timecorrespondingto the proper period of rot'ation 'of seid spot 'or mark by"means Of a time-measuring deviee..and0b serving through said shutterwhen opened and closed the momentary successixe positions of seidrotating spot or mark relative to seid fixed spot or ma1"k.

6. An apparatus for testing rotary registering meters oomprisin'g, inc0mbingtion, a spot or mark upon a rotating partp of the meter to betested, a fi.x6d spot or mark arranged tobe viewed adacent to the;path

thereof whereby its zmgular osition may be measuredg means for measuringthe load uPon said'meter during test, 4and means for momentarilydisclosing to view said spots or proper period of rotation of sa idmeter o1 some multiple or submultiple thereof. 7. An apparatus fortesting rotary registering meter s comprising, in connectin With 40 themete"r to be tested, a spotofmarkon a rotating element thereof, meansfor observing its angular osition from a. fixed spot or mark infractions of a revolution, a lightshutter through which said spob ormark is obseryed, means for measuring a load upon seid meter duringteSt, and a time-measuring de*:ice acting to momentarily open andclosesaid shutter at intervals corresponding to th8 proper period of rotationof said rotating or submultiple thereof. y

8 An apparatus for testing rotary electric moters, oomprisi1ig, inconneotion wit h' a meter to be tested, a spot or mark oarried by arotating elementof said meter, means for measuring the angular positionof said spot or mark from a fixed zero-point, a st'andard load-measdringdez1'cefi arranged 'oircuit With said mepe'r to meaSure the load, alightposition of said pot or mark therethrough, an-electromagneticdez1'ce for operating said shutter, an electric oircuit to energize saidelectromagnetic dev1'ce, a, oircuit-closing device for inaking andbreaking seid circuit,

and a, time-me'as'uring device s'zdapted to 0p* erate saidcirouit-closer to close' seid eircuit at regular intervals of timocorresponding to the Proper period-of rotati on 0f said spot o1 mark,whereby said shutter is momentarily 70' opened and closed.

9. An. appar atus for testing alternatingourrent ro ta.ry lectric meterscomprising, in connection with one of said meters to be tested, astandard load-measuring dexice, an electrie current oirouit carrying the-loa.d to be measured and eontaining said load-measuring dewice, atransformer Whose primary is in4:ircuit with said load-measuring deviceand whose secondary isfin cirouit With said meter, Said transformerhaving a transformation ratio such as to gire a-secondar'y current equal130 a multiple 01 submultiple of the primary ourrent, a spot or mark onrotating .element 0f saidmeter, m'eans for measuring -theangular.position of said spot or mark from a fixed zerooint, and meansfor disclos1ng momentan y to v1ew. ehe suocessrre pos1t1ons of sa1d spotor mnk a t mterrals of -time.corresponding to the joper period ofrota.ti on of said rotatin e em'er'1t or sonne multiple or submultiple t'ie1eof.

'10. An apparatus for teSting al-ternatirig current ro tary wattmeterS,the same 00m- Iirising, in oonnectiom wit-h one of Sa id meters to betes ted a spot o1 merk on a rotating element thereof, a. fixed Spoflormark with re'lztion tp Which the position of said rotating spot or markis obServed; means for mor'nentarily disclosing to view the positions ofseid fixed and rotatin" Spots or marks at intervals corresponding o theproper period of revolution of the latter or somemultiple or submultiplethereof, a standard wattmeasu ring den-1'ce, an elec trie power-eirbuitto be measured, the-potential coils of said mete r and of saidwa'tt-measuring de;ice being conneetedacross the poles of seid circuit,an

electric current-circuitderix=ed therefnom', 1 sa1d cu'rrent-o1reu1t.oonta1nmg regulatmg uneans anal the current coils of said Wattymeas'uring devio'e, a double-polebhang6ozer switch, a secondarycurrent-eirouitin which t11e ounnt-eoils of said met er to be tested areinoluded, and a secondary transformer; the p0les of said twocurrent-circuits and; said transformer being so oonneoted witlisa idswitch that when said switoh is in 0ne osition the two eurrent-oircuitsare in series and said transformer 'is out of aotion and whenseid switchis in the opposito osition said two eurrent-oirouits are seParated andone includ'es the pr'imary o'f seid transformer and the other the'secondary of seid transformer.

In witness whiereof, I haw:e hereunto set my band.

EDGAR M.WILKINS. In p1esenee of' H..G FENTON,

MANUEL LEDUC.

